what is called friction ? what is cause of friction ? how many type of friction?
Answers
Explanation:
Four Types of Friction
Friction is the force that opposes motion between any surfaces that are in contact. There are four types of friction: static, sliding, rolling, and fluid friction. Static, sliding, and rolling friction occur between solid surfaces. Fluid friction occurs in liquids and gases. All four types of friction are described below.
Static Friction
Static friction acts on objects when they are resting on a surface. For example, if you are hiking in the woods, there is static friction between your shoes and the trail each time you put down your foot (see figure below).. Without this static friction, your feet would slip out from under you, making it difficult to walk. In fact, that’s exactly what happens if you try to walk on ice. That’s because ice is very slippery and offers very little friction.
Friction helps this person to walk
Q : Can you think of other examples of static friction?
A : One example is the friction that helps the people climb the rock wall in the opening picture above. Static friction keeps their hands and feet from slipping.
Sliding Friction
Sliding friction is friction that acts on objects when they are sliding over a surface. Sliding friction is weaker than static friction. That’s why it’s easier to slide a piece of furniture over the floor after you start it moving than it is to get it moving in the first place. Sliding friction can be useful. For example, you use sliding friction when you write with a pencil. The pencil “lead” slides easily over the paper, but there’s just enough friction between the pencil and paper to leave a mark.
Q : How does sliding friction help you ride a bike?
A : There is sliding friction between the brake pads and bike rims each time you use your bike’s brakes. This friction slows the rolling wheels so you can stop.
Rolling Friction
Rolling friction is friction that acts on objects when they are rolling over a surface. Rolling friction is much weaker than sliding friction or static friction. This explains why most forms of ground transportation use wheels, including bicycles, cars, 4-wheelers, roller skates, scooters, and skateboards. Ball bearings are another use of rolling friction. You can see what they look like in the figure below.. They let parts of a wheel or other machine roll rather than slide over on another.
Ball bearings reduce friction
The ball bearings in this wheel reduce friction between the inner and outer cylinders when they turn.
Fluid Friction
Fluid friction is friction that acts on objects that are moving through a fluid. A fluid is a substance that can flow and take the shape of its container. Fluids include liquids and gases. If you’ve ever tried to push your open hand through the water in a tub or pool, then you’ve experienced fluid friction. You can feel the resistance of the water against your hand. Look at the skydiver in the figure below.. He’s falling toward Earth with a parachute. Resistance of the air against the parachute slows his descent. The faster or larger a moving object is, the greater is the fluid friction resisting its motion. That’s why there is greater air resistance against the parachute than the skydiver’s body.
FRICTION:−
In our day to day life we use the word friction technically or practically.
▶Friction:- It is a force which oppose the motion or oppose the intension of motion.
❇ Friction is occurs at the point of contact.
❇ The direction of friction is common tangent.
❇ Friction is occur between the two surfaces.
❇ Friction adjust its value automatically and always oppose motion and intension of motion.
StaticFriction:−
❇When two objects having more relative motion between two bodies in contact is called Static friction.
❇Static friction doesn't exist by itself.
❇Static friction help us to start the motion or move.
❇For walking on ground or for starting a motion Static friction is necessary.
LimitingFriction:−
❇ It is the maximum opposing force that comes into play, when one body is just at the verge of moving over the surface of the other body.
OR
It is the maximum value of static friction between surfaces of 2 object if applied force is increase beyond it to the object start, having realtive motion.
❇ To start a object or for starting a motion minimum limiting friction value must be applied.
❇The direction of force of limiting friction is always opposite to the direction in which body have intension to move.
KineticFriction:−
❇ It is the opposing force that comes into play when one body is actually moving over the surface of another body.
In short:- If their is a realtive motion between bodies which is in contact is known as kinetic Friction.
❇ Kinetic Friction help us to stop the motion.
❇ Kinetic Friction is always slightly less than the limiting friction.
❇ Kinetic Friction is also known as dynamic friction.